Known circuit breakers are widely used for medium voltage applications in the range between 1 and 72 kV of a high current level for interruption of electrical circuitries of power grids.
These special circuit breakers interrupt the current by creating and extinguishing the arc in a closed vacuum chamber. Modern vacuum circuit breakers attend to have a longer life expectancy than conventional air circuit breakers. Nevertheless, the present disclosure is not only applicable to vacuum circuit breakers but also to air circuit breakers or modern SF6 circuit breakers.
Generally, a medium voltage circuit breaker includes (e.g., consists mainly of) one or several pole parts, at least one actuator unit and a gear and/or shaft assembly for transmission of the operation force from the actuator unit to the at least one pole part. The number of the pole parts corresponds to the number of phases of the power grid. All these parts are usually accommodated in a common housing. The housing is an integral part of the circuit breaker which cannot be assembled without the housing.
The article “The magnetically actuated circuit breaker reality” (ABB wide paper, ABB power T & D Company, 1999, pages 1-8) discloses such a circuit breaker with a common housing. The same housing is used for accommodating an actuator unit together with a jackshaft arrangement coupled thereon. Separate pole parts have own housings which can include (e.g., consist of) moulded plastics insulating material. The pole part housings are detachably connected on the common housing by screws. The common housing for the actuator unit and the jackshaft arrangement includes (e.g., consists of) a recasted sheet metal housing. The common housing realizes a mechanical connection between the actuator unit and the pole parts which is relatively rigid in order to avoid loss of drive energy. The common housing defines the outer dimensions of the circuit breaker arrangement in order to ensure an attachment interface in a switch board. Therefore, the common housing is normally made of sheet metals. The material is relatively thick to achieve the desired rigidity. In case the common housing of a circuit breaker is made of plastic material, it can be difficult to obtain the specified rigidity without additional steel parts. Different types of switch boards and applications often specify dedicated types of circuit breakers that are different from the very beginning of their production, as they are basing on different housings. This makes an automatic assembly more difficult. A further disadvantage of prior art designs is that a high variance of large and heavy housings presents a logistics problem, especially considering world-wide sourcing.
The patent document EP 0 898 780 B1 discloses a magnetically actuated circuit breaker for medium voltage applications. A single electromagnetic actuator drives a common jackshaft assembly. The jackshaft assembly couples the actuator force to the moving electrical contacts of each pole part containing vacuum interrupter inserts of a pair of electrical contact parts switchable through insulated push rods.
Each pole part has an own housing which is screwed on a mounting surface of a housing which only contains the jackshaft assembly. The housing of the jackshaft assembly includes (e.g., consists of) a recasted sheet metal forming a box which is underside opened in order to gain access to the jackshaft assembly. However, the housing of the actuator unit is not connected to the housing of the jackshaft assembly.
Exemplary embodiments of the present disclosure provide a housing arrangement for a medium voltage circuit breaker which is easy to manufacture and allows an easy mounting of the several parts at one hand and, moreover, which defines a geometrical mounting interface for easily adapting to various different applications.